Highly Robust Rhenium(I) Bipyridyl Complexes Containing Dipyrromethene-BF 2 Chromophores for Visible Light-Driven CO 2 Reduction.

New rhenium bipyridyl complexes with dipyrromethene-BF 2 chromophores (A-ReBDP-CZ, A-ReBDP 2 , ReBDP-CZ, and ReBDP 2 ) were developed for highly efficient photocatalytic carbon dioxide (CO 2 ) reduction to carbon monoxide (CO). These catalysts consisted of two moderate electron-deficient groups (dipyrromethene-BF 2 , BDP) as the visible-light-harvesting antenna as well as both electron donor (N-phenylcarbazole, CZ) and acceptor (BDP) on Re bipyridyl framework. Among ReBDP-CZ and ReBDP 2 complexes, the ReBDP 2 incorporating two electron-deficient BDP chromophores had a longer-lived photoexcited state (182.4 μs) and a twofold enhanced molar absorption coefficient (ϵ=157000 m -1  cm -1 ) compared with ReBDP-CZ. Thus, ReBDP 2 achieved the superior photocatalytic reactivity and stability with a CO turnover number (TON CO ) value as high as 1323 and quantum yield (Φ CO ) up to 55 %, which was the most excellent photocatalysis efficiency among the single-active-site Re catalysts without additional photosensitizer. Furthermore, the acetylene-bridged linker was detrimental to the photoactivity and durability of the catalyst. In brief, two BDP-based Re bipyridyl systems with outstanding catalytic performance and significant visible-light-harvesting capabilities in the solar spectrum offer a promising strategy for solar-to-fuel conversion schemes.